The present invention relates to solar energy collectors in general, and specifically to concentric tube heat exchangers.
Prior art evacuated tube collectors have faced numerous difficulties, the most significant of which is cost. In order to collect a substantial amount of energy per linear foot of concentric vacuum separated tubing, concentrating reflectors or lenses have been employed in conjunction with the vacuum tubes. However, such concentrating devices introduce new and very substantial problems. Unequal linear heating of opposing sides of the tubes results in warpage. High temperatures gained through concentration result in large temperature differences between the concentric tubes and therefore large difference in linear expansion. High temperature differences and rapid temperature rises also produce thermal shock which can shatter glass tubes. Each of these problems has been solved or attempted in previous patents which are too numerous to mention. It is an objective of the present invention to overcome all of the above discussed limitations and other, while introducing few new limitations.